A skid-steer loader, having independently driven sets of wheels on opposite sides of the vehicle as well as a boom assembly carrying work attachments thereon for use with the vehicle requires an effective, compact, efficient hydraulic system for controlling the independent hydrostatic drives for each set of wheels as well as the hydraulic operation of the boom and its attachments. The drive mechanism for the wheels includes a pair of axially aligned hydrostatic pumps, each pump carrying hydrostatic fluid to a hydrostatic motor connected to a chain and sprocket drive for its respective set of wheels on opposite sides of the vehicle. The hydrostatic drive mechanism is interconnected with the hydraulic system controlling the lift and tilt cylinders of the boom assembly of the skid-steer vehicle. A vane pump, axially aligned with the hydrostatic pump, operates to circulate hydraulic fluid to the valve bank controlling the lift and tilt cylinders.
In the prior art, various fittings were interposed between the vane pump and the valve bank to direct fluid from an oil reservoir to the hydrostatic pumps controlling the hydrostatic drive as well as to the valve bank and to the vane pump. In addition, various filters were provided in the hydraulic system to clean and recirculate hydraulic fluid throughout.
In the present invention, a porting block is mounted on the vane pump to control the flow of hydraulic fluid from the valve bank controlling the boom assembly as well as controlling the flow of hydraulic fluid to the inlet side of the hydrostatic motors controlling the hydrostatic drive of the vehicle. In addition, the valve bank is provided with a filter to clean hydraulic fluid as well as a by-pass filter to control the flow of hydraulic fluid. The port block simplifies the hydraulic system of the skid-steer vehicle, eliminates various fittings associated with the control of hydraulic fluid flowing through the system and provides a more compact, efficient hydraulic system for the vehicle.
Other objects and advantages of the present system will become apparent upon a reading of the specification, particularly when considered with the drawings provided in conjunction therewith.